Onset age and disease duration in different countries.

*NA means “not available”, which is due to the different statistical methods. Some studies used “mean” onset age and “mean” disease duration, and others used “median”. “NA” indicates that there was no record of this type of statistic in the methods description.
**We calculated the mean onset age in Australia based on the number of cases (351), the mean age at death (65.3 years) and the mean duration (6.6 months) mentioned in the referenced report [9].
***The twelve countries are Argentina, Belgium, Canada, France, Germany, Italy, the Netherlands, Australia, Portugal, Slovenia, Switzerland and the United Kingdom [2].